This multicenter, open-label long-term study is a followup to the placebo- controlled study to determine a) the safety and b) the efficacy of oral tizanidine in reducing excessive muscle tone associated with spasticity in patients with multiple sclerosis. This study will determine the safety of long-term treatment with tizanidine at maximally tolerated dosage of up to 12 mg three times a day. This study was completed with FDA approval of tizanidine with an indication for use for treatment of spasticity associated with multiple sclerosis.